Safety shield for pad mounted electrical transformers



Sept. 2, 1969 R. G. JONES 3,464,580

SAFETY SHIELD FOR PAD MOUNTED ELECTRICAL TRANSFORMERS Filed March 6, 1968 2 Sheets-Shet 1 I N VEN TOR foaawzs. JO Vl;

WaW/MUW ATTOR NEYS Sept. 2, 1969 R. G. JONES 3,464,530

SAFETY SHIELD FOR PAD MOUNTED ELECTRICAL TRANSFORMERS Filed March a, 1968 2 Sheets-Sheet 2 United States Patent US. Cl. 220-18 5 Claims ABSTRACT OF THE DISCLOSURE An enclosure for a ground supported electrical transformer including pad mounting means for the transformer, a shield extending around and over the transformer and supported on the pad, means releasably locking the shield on the pad, and means for venting the shield to the ambient atmosphere.

BACKGROUND OF INVENTION The development of the shield means to which this invention pertains has been spurred primarily by the recent trends in the beautification of congested areas as well as in urban developments. Utility service beautification has been urged recently by power consumers, conservation groups, officials of towns and cities, and by the Federal Government. Development of materials and hardware for underground direct burial of primary and secondary service conductors has also aided in the advancement of powed distribution beautification. However, the transformers used for this service are of special nature and cause problems with regard to economics, service and interchangeability. Two basic designs have been prominently developed for use with underground distribution systems, namely, pad mounted transformers and submersible transformers. This invention involves the former.

In the prior art practices, pad mounted transformers are usually special adaptations of combining sheet metal enclosures with the transformer tank and providing these units require special stocks of these transformers in order to be able to interchange the units when one is damaged or for other service or maintenance requirements. Maintaining a stock of these special transformers is not, at the present, economically feasible.

In the process of designing the shield according to the instant invention, the following factors were of prime consideration. Municipal power utilities, private power utilities, and the rural electric cooperatives, all of which use the standard pole type transformer all maintain adequate stocks of this type of transformer. In addition, many of the above named power distributors maintain repair parts stocks and have educated their personnel in the maintennance and repair of pole type transformers. It is the aim of this invention, therefore, to incorporate as many of the above assets into the new underground trend as is feasible, while still and at the same time directing such developments to the areas of safety, economy, beauty, simplicity and flexibility.

Therefore, one of the primary objects of this invention is to provide a fiberglass reinforced polyester resin material in the construction of the shield to provide both dielectric and mechanical strength.

Another object of this invention is to provide a transformer shield of the type to which reference has been made in which it is impossible for metal parts to contact any electrical wires or devices and provide high potentials to ground which would be dangerous to persons or animals coming in contact with the shield or enclosure.

A further object of this invention is to provide a bafiling and ventilation system whereby adequate cooling is pro- Patented Sept. 2, 1969 Ice vided for the transformer while at the same time eliminating the possibility of children inserting wires and other objects into the ventilator openings and effecting contact with high potential electrical parts within the shield 0r enclosure.

Still another object of this inventon is to provide a shields may be molded to economically compete with standing high impact forces and severe shocks which may be the outgrowth of rock throwing and other forms of vandalism.

It is a still further object of this invention to provide a transformer shield or enclosure which serves adequately for mechanical protection over extremes of temperature ranges.

Still further, it is another object of this invention to produce shields of the type described supra, wherein the shields may be molded to ecnomically compete with metallic counterparts which do not offer the safety advantages of the nonmetallic shield according to this invention.

Again, it is one of the objects of this invention to provide a molded pigmented premixed polyester resin material to provide easy coloring methods in order to produce a pleasing color for blending purposes in landscaped areas receiving utility services.

Still another object of this invention is to provide a substantially hollow cylindrical transformer shield wherein the geometric configuration, per se, eliminates unaesthetic lines due to the provision of doors, protrusions and other component elements found in conventional enclosures utilized in pad mounted transformer units.

It is a still further object of this invention to provide a low silhouette safety shield for an electric transformer wherein the overall height of the enclosure is lower than the prior art devices while still providing for the economical use of the pole type transformer.

This invention contemplates, as still a further major object thereof, the provision of a transformer safey shield for a pad mounted electric transformer in which simplicity of design and construtcion play dominant parts and is achieved through the use of fiberglass and polyester materials, and this has the further advantage of providing light-weight units which may be easily handled. The simplicity in construtcion avoids complex assembly normally required at the locus of the transformer and involves but a two piece assembly for installation. In emphasizing the simplicity of construction, protective pockets for the releasable latch or locking mechanism also serve as alignment guides to insure immediate and accurate placement of the enclosure over the transformer, and the latching mechanism, per se, is especially designed for simplicity to avoid complex mechanisms which may become fouled, misaligned or damaged.

Still a further object of this invention is to provide a shield of the type generally described above which will not rust, deteriorate, and which is permanently colored thereby eliminating the necessity of maintenance and painting.

Other and further objects and advantages of the instant invention will become more manifest from a consideration of the following specification when read in conjunction with the annexed drawings.

SPECIFICATION In the drawings:

FIGURE 1 is a detail medial vertical transverse crosssectional view of a safety shield for a pad mounted electrical transformer, the latter being shown in phantom lines;

FIGURE 2 is a fragmentary detail cross-sectional view of the shield shown in FIGURE 1, FIGURE 2 being taken substantially on the horizontal plane of line 22 of FIGURE 1, looking in the direction of the arrows;

FIGURE 3 is an enlarged fragmentary detail crosssectional view, FIGURE 3 being taken substantially on the line 3--3 of FIGURE 4, looking in the direction of the arrows;

FIGURE 4 is a fragmentary detail cross-sectional view, FIGURE 4 being taken substantially on the horizontal plane of line 44 of FIGURE 3, looking in the direction of the arrows; and

FIGURE 5 is a fragmentary detail transverse crosssectional view, FIGURE 5 being taken substantially on the vertical plane of line 55 of FIGURE 3, looking in the direction of the arrows.

Referring now more specifically to the drawings, reference numeral designates a pre-prepared bed preferably formed of gravel or crushed stone 12 of suflicient depth to support a pole type transformer and the apparatus according to this invention. The bed 10 is also utilized to facilitate drainage.

Superimposed on the bed 10 is a substantially cylindrical cement pad 14 having appreciable thickness and an upper side or surface 16. For practical purposes, the pad is shown and described herein as being cylindrical although obviously the same may have any configuration as may be dictated by circumstances. The pad 14 construction, per se, is completed by providing at least on transversely extending conduit receiving passage 18 (see FIGURES 1 and 2) which opens at one end into the plane of the upper side or surface 16 and at its other end into the plane of the underside or surface 20 of the pad 14. The passage 18 receives therethrough one of the ends of an underground primary conductor and of underground secondary leads for service connection, neither the conductor nor leads being shown in the drawings since the same do not comprise subject matter of this invention.

At 22 is denoted a vertically elongated hollow cylindrical hold down ring integrally or otherwise fixedly connected to a plurality of inwardly projecting, preferably radially extending, normally horizontal connector flanges 24, and the latter, in turn, are fixedly connected to the pad 14 by anchor bolts 26 or other conventional and suitable connector means. The anchorage is such as to cause the lower circumferential edge 28 of the ring 22 to fit substantially coplanar with the plane of the upper surface or side 16 of the pad 14.

Reference numeral 30 indicates, in general, one of a plurality of hold down brackets each of which, structurally, has an inverted substantially L-shaped configuration including an elongated substantially flat rectangular leg portion 32 having its lower end abutting selected ones of the flanges 24 and superimposed against the inner side of the ring 22 to which the leg portion 32 is fixedly connected by conventional means, not shown. The upper end of each leg portion 32 terminates in a radially inwardly extending foot section 34 integrally or fixedly connected therewith.

As is seen in FIGURES 1 and 2, the passage 18 is disposed inwardly of the hold ring 22 and the latter circumscribes a conventional pole type electrical transformer 36 (shown in phantom lines in FIGURE 1) and which is substantially centered therein.

The safety shield or enclosure constructed in accordance with the teachings of this invention bears the general reference numeral 40. The shield 40 comprises a vertically elongated substantially hollow cylindrical main body portion 42 integrally connected at its lower peripheral edge with a downwardly and outwardly inclined continuous circumferential flange 44, and the outer peripheral edge of the latter continues into a depending first cylindrical weather and guard skirt 46 disposed in outwardly spaced concentric relation relative to the main body portion 42. As is seen in FIGURE 1, the main body portion 42 adjacent its upper end 48 is formed with a plurality of 4 transversely extending circumferentially spaced, at regular intervals, vent openings 50.

Reference numeral 52 denotes a second substantially hollow cylindrical guard skirt having a diameter somewhat less than the diameter of the main body portion 42, and a lower peripheral end edge 54. The upper end of the skirt 52 is integrally connected with an upwardly and outwardly inclined continuous circumferential flange 56, and the latter, at its upper end is integrally formed with a continuous hollow cylindrical lip 58 concentrically related to the skirt 52 and having an outer diameter substantially equal to the inside diameter of the main body portion 42.

As is seen in FIGURE 1 of the drawings, the lip 58 is fitted within the lower end of the main body portion 42 and is superimposed on a marginal portion thereof immediately adjacent its junction with the upper end of the flange 44. The superimposition between the lip 58 and the main body portion 42 is such that a small inner marginal edge portion 60 (see FIGURE 1) of the lip 58 is disposed in confronting spaced relation relative to the upper end of the flange 44 so as to provide a downwardly opening continuous cylindrical pocket 62 to serve a function to be described. The lip 58 and the main body portion 42 are fixedly connected together by conventional means, but the preferred connecting means comprises a polyester cement (not shown). As is seen in FIGURE 1, the lower peripheral edge 54 of the guard skirt 52 is disposed well below the lower peripheral edge 64 of the skirt 46.

Reference numeral 66 denotes a third hollow cylindrical guard skirt having a lower peripheral marginal edge 68 and which, at its upper end, continues into an upwardly and outwardly inclined continuous circumferential flange 70, and the outer end of the latter is integrally connected with an upright second continuous hollow cylindrical lip 72 disposed in spaced concentric relationship relative to the skirt 66. The lip 72 has an outside diameter substantially equal to the outside diameter of the main body portion 42 against which it is superimposed at the marginal edge portion thereof extending above the vent openings 50 and below its upper end 48. The lip 72 is fixedly connected to the main body portions 42 by conventional means, though as described supra in relation to the connection of the lip 58 with the main body portion 42, the preferred means comprises a polyester cement. With this connection being effected, the skirt 66 is disposed in inwardly spaced and confronting relationship with respect to the vent openings 50 and, from the foregoing description, it is seen that both the first and second guard skirts 52, 66, respectively, are disposed in inwardly spaced concentric relation relative to the main body portion 42.

The upper end 48 of the main body portion 42 is provided with a transversely extending concave-convex closure plate 74 which rests thereon and which is fixedly and rigidly connected thereto and to the upper end of the lip 72 (which is coplanar with the end 48) by conventional means such as, the aforementioned polyester cement. As is seen in FIGURE 1, the closure plate 74 is integral with the upper end of a depending continuous hollow cylindrical fourth weather and guard skirt 76 which is disposed in circumscribing circumferential outwardly spaced and concentric relationship relative to the main body portion 42. The axial length of the skirt 76' is such that its lower end 78 is disposed below the vent openings 50 as is the lower peripheral end 68 of the skirt 66, and as is seen in FIGURE 1, the end 68 is positioned lower than the end 78 of the skirts 66 and 76, respectively.

Reference numeral 80 indicates a lower vertically elongated substantially hollow cylindrical sidewall having a lower open peripheral circumferential end 82 and a similar opposed upper end 84. Vent openings 86 extend transversely through the upper marginal edge of the sidewall 80 in circumferential radially spaced intervals.

The upper end 84 and marginal end portions adjacent thereto are received within the pocket 62 in which they are fixedly connected as by a polyester cement (not shown). The main body portion 42 and the sidewall 80 are coaxially aligned and have identical diameters each of which is greater than the outside diameter of the ring 22. Thus, with the main body portion 42 and the sidewall 80 connected as described above, and in the assembly of FIGURE 1, a lower marginal end portion of the end wall 80 is disposed in spaced concentric and confronting relationship relative to an adjacent portion of the ring 22.

As has been mentioned supra, this invention contemplates releasable locking means which is here identified by the general reference numeral 90 and which cooperates, in a manner to be described infra, with the foot section 34 of one or more of the hold down brackets 30, it being understood that one such means is provided for each bracket, respectively.

At the location of each locking means 90, the sidewall 80, intermediate its upper and lower ends 82, 84, respectively, is formed with an inwardly projecting integral boss 92 (see FIGURE 3), and the sidewall 80 and the boss 92 are formed with a continuous tapped opening 94 extending transversely therethrough.

An axially elongated cylindrical brass bushing 96 externally threaded at 98 and provided with an enlarged outwardly extending hexagonal flange 100 at one end thereof is threadedly engaged within each of the tapped openings 94 until the flange 100 abuts the outer side of the sidewall 80. In this position, the bushing 96 has an opposed end extending radially inwardly of the sidewall 80 and beyond the boss 92, this end of the bushing receiving a brass lock nut 102 thereon to secure the bushing 90 against displacement from within the opening 94.

The bushing 96 is provided with an axially extendnig smooth cylindrical bore 104 which opens into the planes of the opposed ends thereof and in which the leg portion 106 of a substantially L-shaped latch bar 108, cylindrical in transverse cross-section, is fitted for rotation about its longitudinal axis. The latch bar 108 also includes an integrally connected laterally projecting foot section 110 having a function to be described below, and from FIG- URE 4 it is seen that the longitudinal axis of the leg portion 106 and the foot portion 110 are substantially perpendicular with respect to one another. The distal end of the foot section 110 is formed with a diametrically extending tapped opening 112 having a vertically extending axis when the bar 108 is in its operative positions of FIGURES 3 to 5, inclusive. Threaded into the opening 112 is the externally threaded shank 114 of an elongated screw or bolt 116 having an upper enlarged head 118 slotted as at 120 to receive the blade of a screwdriver or other tool blade whereby axial adjustment of the screw 116 will vertically shift the head 118 to an adjusted position to serve a function to be explained below, and the adjusted position of the bolt 116 and consequently, its head 118, is maintained by a conventional lock nut 120 threaded on the lower end of the shank 114 and which is moved into tight abutting relationship relative to the underside of the adjacent foot section 110.

Welded or otherwise fixedly secured to the outer end of the leg portion 106 of the latch 108 is a substantially rectangular hinge plate 122. At 124 is denoted an elongated substantially rectangular hasp which, in its operative position, extends substantially vertically as viewed in FIGURE 3, and the lower adjacent ends of the hinge plate 122 and hasp 124 are connected together by conventional hinge means 126. The hinge connection means 126 is such that the other end 128 of the hasp 126 is pivotal about a normally horizontal axis towards and away from its confronting operative position shown in FIGURES 3 to 5, inclusive. To serve a function to be described, the hasp 124 adjacent its upper free end 128 is provided with a transversely extending horizontally elongated slot 130 (see FIGURE 3).

locking means (not shown). The opening 130 is of such size as to conveniently receive the tongue 138 when the hasp 124 is in its operative position of FIGURE 3, but it is not so large as to permit disengagement of the hasp 124 with the tongue 138 when the above-mentioned locking means is positioned within the opening 140.

The hold-down bracket 30, the inner end of the bushing 96, and the inwardly exposed portions of the latch bar 108, its adjacent screw or bolt 116, and the lock nut 120 are all protected from such moisture or condensate as may be blown through the vent openings 50 and 86 or which may collect thereon to drip and run thereover, the portection means comprising a housing generally indicated by reference numeral 150. The housing 150 opens downwardly and may be molded of a plastic material to include an inverted substantially V-shaped top wall 152 having downwardly diverging arms 154, 156 which, at their remote ends, are integrally connected with a pair of depending flanges 158, 160, respectively, the latter terminating in end edges 162, 164 disposed in a plane positioned below the plane of the peripheral end edge 54 of the skirt 52. Secured or integrally connected to the arms 154, 156, and the flanges 162, 164 and extending across one side of the housing 150 is a back closure wall 166. The front edges of the housing 150 are fixedly secured to the sidewall as by a polyester cement (not shown) or other conventional means, and the skirt 52 is provided with downwardly opening complementary openings 168 (only one being shown) to receive the arms 154, 156 and adjacent portions of the flanges 162, 164 of each housing 150 therein. If desired, the housing portions confronting the contiguous edge of the openings 168 may be secured thereto as hereinbefore described to provide rigidity for the structure. As is seen in FIGURES 3 and 5, the arms 154, 156 span the interior components of the locking means and the adjacent hold-down bracket 30 with the flanges 160, 162 extending across their respective remotely disposed sides.

The main body portion 42 and the components mounted and carried thereon with the exception of the hardware of the lock means 90 are preferably formed of a suitable light-Weight plastic material such as, for example, fiberglass polyester resin materials which may be optionally pigmented to fit into the adjacent landscape. Obviously, other materials may be used in the practice of this invention without departing from the spirit and scope thereof.

The utility of this invention is clearly shown in FIG- URE 1 of the drawings wherein the transformer 36 is shown within the confines of the shield 40, and if it be assumed that the latter is locked to the base or pad 14 in its operative position, the component elements of the invention will be in their respective associated positions as is shown in the several figures of the drawings.

To remove the shield 40 from its associated pad 14 it is only necessary to remove the mechanical look (not shown) from the opening (see FIGURE 3) and to pivot the hasp 124 in clockwise direction about the hinge means 126 and to disengage the hasp 124 from its staple 136. The hasp 124 is now employed as a manually operable lever to turn the latch bar 108 in a clockwise direction, reference being made to FIGURE 5 of the drawings, tocause the enlarged head 118 to disengage from under the foot section 34 of the hold-down bracket 30 associated therewith, the turning action taking place through an arc of sufficient length in order that in the subsequent lifting of the shield 40 away from its associated pad 14 to remove the shield upwardly from over the transformer 36, the adjustment screw 114 and its head 118 clear and will not inadvertently or accidentaly reengage with the foot section 34. After the transformer 36 has been inspected, repaired, or other work performed in connection therewith, the shield 40 may be quickly and easily replaced and reconnected to its pad 40 by repeating the above steps in the reverse order and direction.

The hold-down tension of the locking means 90 is quickly and easily achieved by the adjustment of the screw 116 to shift the head vertically relative to the foot section 34.

While the above specification recites separate steps for the cementing of several of the components of the shield 42 with one another, it will be recognized that some ones thereof may take place substantially simultaneously, for example, the lip 58 may be secured to the inner side of the main body portion 42 substantially simultaneously with the cementing of the upper end 84 of the sidewall 80 within the pocket 62.

The vent openings 50 and the guard and weather skirts 66 and 76 adjacent thereto as well as the vent openings 86 and the weather and guard skirts 46 and 52 cooperate to provide suflicient ventilation for the transformer 36 and reduce to a minimum the amount of dust, dirt and other debris which may be blown into the shield 40. Additionally, the vertical lengths of the several described skirts are such as to successfully prevent immature persons and/or vandals from introducing wires, sticks, and other elements into the shield to engage with current carrying contacts of the transformer 36 to cause physical injury to such persons and/or to short out or otherwise damage the transformer.

What is claimed is:

1. A shield or enclosure comprising a base pad;

a substantially hollow member having opposed open ends; closure means for one open end of said member, the other open end thereof being engaged against said P cooperating latch means on said pad and member and disposed within the latter to releasably secure said member on said pad;

said latch means including bracket means fixedly connected on said base pad and having a first section thereof disposed in spaced relation relative thereto, a latch bar means rotatably mounted on said member and having a portion thereof disposed inwardly of said member and being rotatable into an out of engagement with said first section; and

lever means connected on said latch bar means externally of said member and operable to effect actuation of said latch bar means.

2. A shield or enclosure comprising a base pad;

a substantially hollow member having opposed open ends;

closure means for one open end of said member, the other open end thereof being engaged against said P cooperating latch means on said pad and member and disposed within the latter to releasably secure said member on said pad;

said latch means comprises a plurality of inverted substantially L-shaped brackets each having a leg portion and a foot section with said leg portions secured to said base pad and said foot sections converging towards one another in vertically spaced relation relative to said base pad;

said latch means further including a substantially L- shaped latch bar for each cooperating bracket, each of said latch bars including a leg portion journalled for rotation on said member adjacent its cooperating bracket and a foot section disposed inwardly of said member, said foot section of said latch bar being rotatable between said base pad and said bracket foot section to engage said foot section of said bracket;

lever means connected on said leg portion of said latch bar and disposed externally of said member and being operable to effect engagement and disengagement of said latch bar foot section with said bracket foot section.

3. The combination of claim 2 and wherein said lever comprises a hasp having an end thereof hingedly connected on said leg portion of each latch bar;

staple means on said member; and

means on said hasp releasably receiving said staple therethrough to alford a mechanical connection therebetween.

4. In the combination of claim 3 wherein adjustable means are mounted on said latch bar foot section for engagement with its associated foot section of the adjacent bracket to clamp said member on said base pad under adjusted degrees of tension.

5. In the combination of claim 4 and a plurality of circumferentially spaced vent openings formed in said member intermediate the ends thereof; and

guard means fixedly secured to said member, said guard means being disposed internally and externally of said member and in laterally spaced and confronting relationship relative to each of said vent openings.

References Cited UNITED STATES PATENTS 2,227,990 1/ 1941 Zelt 22044 X 2,724,968 11/ 1955 Greene 73-201 FOREIGN PATENTS 1,032,673 4/ 3 France.

GEORGE E. LOWRANCE, Primary Examiner US. Cl. X.R. 

